Mechanism of Phosphorus Release of Phosphorus-Rich Waste Activated Sludge under Anaerobic,Anoxic and Aerobic Conditions

The phosphorus release mechanism of phosphorus-rich waste activated sludge under anaerobic,anoxic and aerobic conditions was investigated with three brown anaerobic reactors.The waste activated sludge was obtained from a sewage treatment plant in which the(A/O) process(an enhanced biological phosphorus removal process) was used.The results indicated that the phosphorus release of waste activated sludge could be observed clearly,and the release velocities were 1.614 and 0.998(mg/(L·d)) under anaerobic and anoxic conditions respectively. The metrology relationship between the changes of phosphorus and PHB suggested strongly that there were two phosphorus release mechanisms in phosphorus-rich waste activated sludge.One was the microbiological mechanism,which accounted for main phosphorus release,and the other was physicochemical.The phosphorus release under anoxic conditions was restrained to a certain extent due to the addition of(NO_3~——N).